风车案例案例:

关键代码:
transform: rotate(120deg); 旋转120度。
transition:2s; 旋转120度花2秒完成。

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			*{
				margin: 0;
				padding: 0;
			}
			html,body{
				height: 100%;
				overflow: hidden;
			}
			
			#wrap{
				width: 300px;
				height: 300px;
				position: absolute;
				left: 0;
				right: 0;
				top: 0;
				bottom: 0;
				margin: auto;
				transition:2s;
				border: 1px solid;
			}
			#wrap > div{
				margin: 10px;
				width: 130px;
				height: 130px;
				border: 1px solid;
				background: deeppink;
				float: left;
				box-sizing: border-box;
			}
			#wrap > div:nth-child(1),#wrap > div:nth-child(4){
				border-radius:0 60%;
			}
			#wrap > div:nth-child(2),#wrap > div:nth-child(3){
				border-radius:60% 0;
			}
			
			#wrap:hover{
				transform: rotate(120deg);
			}
		</style>
	</head>
	<body>
		<div id="wrap">
			<div></div>
			<div></div>
			<div></div>
			<div></div>
		</div>
	</body>
</html>